Review on Ecology of Rain Forest

The tropical rainforest is the place on Earth where the most different kinds of plants and animals live. It is also known as a tropical wet evergreen forest. This special forest is   found near the equator, where it rains a lot—more than 2,000 mm every year! It only has a few short dry weeks when it doesn’t rain much. Because of all the rain, the plants grow really well, and most of the trees stay green all year long (Mudappa, D., & Raman, T. R. S. (2010). On the forest floor, you can find many plants like herbs, shrubs, ferns, and flowers called orchids. Some plants, known as epiphytes, even grow on the branches of other trees! The bark of trees and the surfaces of leaves are home to tiny plants, fungi, and mosses. All these different plants create a rich environment that supports many animals, from tiny bugs in the soil to big animals like elephants and birds called hornbills. All these living things work together to make the rainforest a special place (Mudappa, D., & Raman, T. R. S. (2010) Tropical rainforests are the most complex ecosystems on Earth. For literally millions of years, rainforests—which many people refer to as jungles—have dominated tropical flora. There may be a diversity of organisms beneath their soaring canopy that is unmatched anywhere else on the planet. (Park, C.C. 1992). High temperatures with little variation throughout the year are found in rainforest regions. Throughout the year, temperatures hover around 20°C to 28°C, with the warmest months in a particular location maybe being a degree or so warmer than the coldest. Because the sun lies primarily above, there are not many fluctuations in the length of daylight throughout the year, which leads to this homogeneity. (Baur, G. N. (1964) Rainforest can be defined as a closed community of essentially, but not exclusively, broadleaved, evergreen, hygrophilous trees, usually with two or more layers of trees and shrubs, and with dependent synusiae of other life-forms, such as climbers and epiphytes.   (Baur, G. N. (1964)

Climate of Rainforest

A variety of meteorological elements that are crucial to the growth of any vegetation make up the climate. At its core, it is a measurement of the atmosphere's capacity to supply the environment with heat, moisture, airflow, and light. (Baur, G. N. (1964) Climate exerts a strong influence over the broad distribution of rainforests within the tropics. It also has a marked effect on regional patterns and structures of rainforest vegetation and habitat. Rainforests occur in hot moist climates. They receive more solar radiation throughout the year than any other vegetation zone on earth, which promotes the rich variety and luxurious character of vegetation. (Baur, G. N. (1964) The typical rainforest climate has two main distinguishing features—relatively constant temperatures, and heavy rainfall. Tropical forests grow under a narrow range of temperatures but a fairly wide range of precipitation. The combination of these two climatic controls secretes the very special environment for rainforest growth Temperatures in rainforest areas are high, and they vary relatively little throughout the year. Temperatures remain fairly constant at between 25°Cand 30°C through the year, the warmest months perhaps a degree or so higher than the coldest months in a given place. This uniformity occurs because the sun is mostly overhead, so variations in the length of daylight throughout the year are limited. (Aiken, S. R., & Leigh, C. H. (1986).

RAINFALL

Rainfall is important ecologically by providing a crude, though nonetheless most convenient, measure of the capacity of the site to supply moisture for the growth of plants. (Baur, G. N. (1964) the rainfall limits for evergreen seasonal rainforest in tropical America are stated to be an annual total of 70 inches, with three months each under 4 but over 2 inches, and to be between 50 and 70 inches, with five months each under 4 inches but over 1 inch. (Richards, p. 317).  In Nigeria, (Keay 0959a) gives an annual rainfall of 48 inches as marking the boundary of the rainforest zone, though this value is modified by humidity. In the tropics, rainforests can be found far beyond these minima along stream banks and in other places where the topography or soil provides favourable moisture conditions. They may not be present in wetter regions where the soil has a limited ability to hold onto moisture. (Baur, G. N. (1964) Thus, the excessively drained limestone soils in parts of the West Indies carry semi -deciduous forest formations though the annual rainfall exceeds 60 inches, and the seasonal drought is not lengthy (Beard, 1946a; Gleason and Cook, 1926) On the other hand, well developed evergreen seasonal rainforest occurs on the deep, well structured, heavy textured soils of the "Planalto" (low plateau) around the C. B.A. station near Santarem, on the Amazon River, though apparently reliable records from C. B.A. stretching over eleven years indicate a mean annual rainfall of only 34 inches, with seven months under 4 inches.

Other Atmospheric Moisture

The site receives atmospheric moisture from a variety of sources, including rainfall, and atmospheric moisture has a variety of ecological effects. While the amount of moisture vapor in the air can have a significant impact on the evapotranspiration rate, tiny amounts of moisture can also be obtained by condensation in the form of dew and mist, as well as from snow and hail falls as one advances farther from the tropics. Snow is by no means unusual in the temperate climate zone where rainforests occur, but it cannot be considered an essential supply of moisture for rainforests, with the possible exception of some of the very high latitude temperate rain forests in South America. (Baur, G. N. (1964). Snowfalls are therefore sporadic above 2,500 feet and nearly yearly above 3,500 to 4,000 feet in northern New South Wales (lat. 28–32° S), where even subtropical rainforests still exist in a few locations. Unusually high snowfalls at these elevations are likely to cause some of the crown damage to rainforest trees.  (Baur, G. N. (1964). Although the incredibly abundant epiphyte flora of Montaine rainforests should be largely attributed to the frequent mists that envelop most tropical mountains, atmospheric water vapor is generally of relatively little importance as a direct source of moisture for plant growth. Similar effects can be seen in the temperate rainforest zones. However, by lowering evapotranspiration rates, especially during times of low rainfall, atmospheric water vapor can have a significant ecological impact. (Baur, G. N. (1964). In rainiest areas, relative humidity is typically high and approaches saturation point most evenings. Nonetheless, throughout the day, particularly during the dry seasons, quite low humidity levels are possible. Therefore, during the dry season, the extremely dry "harmattan" wind that sweeps southward over West Africa from the Sahara can significantly lower the relative humidity in the rainforest belt for a few days at a time and Keay (1959a) considers that the low humidities associated with this phenomenon are as important as rainfall in determining the limits of rainforest occurrence in Nigeria.

Temperature

Given its extensive latitudinal and altitudinal range, rainforests in all of their varieties should be able to withstand a wide range of temperatures. Both latitude and altitude affect the mean yearly temperature. Up to roughly 15 latitudes, the mean temperatures for low altitude stations vary very little. After that, they progressively drop to the area around the geographic tropics, and then they increase steadily as latitude increases. Similar to this, the temperature in mountains drops rather steadily as height rises. The exact rates of temperature decline vary significantly depending on the local land and sea configuration; on average, values seem to be about a 1° F drop in mean temperature for every degree of height gain or for every 250–300-foot increase in elevation.  (Baur, G. N. (1964). Compared to tropical species, temperate species grew at their fastest rates at cooler temperatures. Nonetheless, throughout the temperature range employed, there was a significant overlap in the growth rates of the tropical and temperate rainforest types. Changes in biomass allocation were linked to the maximum growth of the tropical rainforest types, while there were no discernible changes in biomass allocation across the temperature range for the temperate rainforest types. (Baur, G. N. (1964).

Soil

Light is the microclimatic component that most likely exhibits the widest range of circumstances within a rainforest, from the upper canopy to the ground level. Similar to vegetation, soil type is not an independent environmental element in and of itself; rather, it is the outcome of other factors interacting with the parent material of the soil, which is one of the independent factors influencing vegetation. (Baur, G. N. (1964).Plant growth depends on soil in a number of ways. In addition to directly or indirectly supplying the nutrients and moisture that plants need, it offers the physical support and anchorage essential before any tree growth is feasible. (Baur, G. N. (1964). An important "ecological service" is provided by the ecosystem processes that take place in the soil, where 60 to 90% of terrestrial primary production is broken down. Detritivores soil animals are essential to decomposition because they break up litter, crop microbial populations, which increases their metabolism (MacLean, C. D. (1988). Macrofauna can process up to 30% of the annual dead organic matter input to most soils (Dangerfield, 1990) and termites alone have been recorded to consume about 20% of litterfall in Ghanaian forests (Usher, 1975) the paedogenetic mechanisms that result in the landscape's various soil types. Physiography had an impact on pedogenesis, which led to a variety of soil types throughout the terrain. Depending on the location of the Pedon’s on the landscape, distinct soil types were created when comparable parent material was present because of varying exposure to morphogenesis processes such eluviation, illuviation, deposition, cementation of Pedi sediments, and multiple stratification.  (Ande, O. T. (1995).  The bulk of dry land rainforest soils are the result of the combined processes of laterization and podsolization. Both are linked to the quick draining of soil bases, which causes the apparent paradox of incredibly lush flora flourishing on the majority of barren soils, especially in the tropics. (Barnard, R. C. (1956). The roots of the rainforest plants are largely confined to the upper soil layers, but in well drained soils may ramify to a depth of six feet (Beveridge 1957) As previously mentioned, rainforest soils typically, though not always, lack plant nutrients, and it is likely that fertility—more than any other factor—provides the primary production limit for rainforest sites over substantial areas. Although the plants are obviously well suited to using the nutrients that are available as efficiently as possible, it is evident that the species that are found on the most infertile rainforest soils—such as tropical podsol’s and peat swamps—are primarily chosen based on their capacity to withstand low nutrient levels. (Baur, G. N. (1964).

Topography

Topography is the independent environmental component. Climate and soil work together to influence the vegetation, and while topography has a significant local impact.  it has a less significant role overall in determining the composition and structure of rainforests than the other two categories of elements. In actuality, the effects of topography can be roughly divided into two divisions based on how they alter the climatic and edaphic elements, respectively. A few instances should be enough to demonstrate these effects. (Baur, G. N. (1964). topography can significantly change the climate of regions that are geographically close to one another and within the same altitude range at a more local level. This can happen in a number of ways and involves various climatic characteristics. One of the most significant effects of topography on vegetation distribution is wind exposure, which is mostly dictated by topography climatic conditions in the higher topographic positions adjoining these fringing belts of rainforest are suitable for the developing of rainforest, as in the "derived savanna “region of Nigeria (Keay, 1959a) There are additional functions of topography in managing rainforests. The topography has a significant impact on compartment subdivision. A rectangular subdivision can be superimposed almost at will in the even relief of the southern Nigerian rainforests or the Amazonian Planalto, but this is impractical in hilly or mountainous topography, like that found in Malaya, and compartments must be based on local relief features. (Barnard, R. C. (1955) The report on silvicultural systems for rainforest in the Asia-Pacific region (F.A. 0., 1960b) notes that one of the factors favouring mechanized logging is the occurrence of flat topography, while in the mountainous rainforest terrain of Ceylon tractor logging is forbidden

Biotic Factor

Like all forest communities, rainforests are made up of plants, provide shelter to a variety of animals, including humans, and maintain a rich fauna of invertebrate’s microscopic microorganisms in the soil beneath them. Together, these make up the biotic factor, which is partially dependent on the rainforest itself and partially independent of the local flora and fauna. As with the other environmental factors, an understanding of the significance of this factor is necessary before any attempt to manage the rainforest can be made. (Baur, G. N. (1964).

Flora

The most divers forest on earth is the tropical rainforest, which is home to large-buttressed,

Broad leaved trees as well as climbers, epiphytes, and hemi epiphytes. They are rich in flora diversity and feature a multi-layered canopy, which includes upper, intermediate, and dense understory vegetation composition. A vast array of plant species can be found in tropical rainforest. Four different tree layers – emergent, upper canopy, understory, and forest floor make up the vegetation species composition of rainforests. (Baur, G. N. (1964).

Fauna

With their ability to pollinate a wide range of plant species, disperse seeds, control pest populations and lessen the damage caused by various pest species, scavenge carcasses, and recycle nutrients back into the soil, faunas play a crucial role in the ecosystem of tropical rainforests and offer a wide range of environmental services. (Baur, G. N. (1964).